Image forming devices commonly include a plurality of motor control systems to drive various image forming components. For example, one motor control system may be used to drive one or more photoconductive members, including drums, plates, or belts, while another motor control system may be used to drive another component, such as a transport belt, intermediate transfer belt, developer roller, or transfer roller. Furthermore, in some image forming devices, the image forming components are placed in moving contact with one another.
Various considerations arise during the initial startup and acceleration of the image forming components from rest to a process speed. For example, friction exists at the contact surface between components if one component accelerates at a faster rate than another. Significant amounts of friction may produce excessive heat, wear, and power consumption. Another concern relates to image quality. Ideally, image-forming components that are placed in moving contact with one another move at substantially uniform surface speeds with respect to one another. Image smear or image misregistration may result if an image transfer occurs between components that are not at a desired speed or position. Generally, once components reach a steady-state process speed, their respective motor control systems can control the speed and/or position of the components within desired limits. However, when components are accelerating, matching surface speeds may be difficult.
In addition, backlash in a motor gear train may contribute to position errors. Generally, backlash in a gear train should be removed in order for a motor to positively drive a component and for an associated motor control system to control the speed and position of that component. Unfortunately, in certain instances, the interplay of accelerating components that are in contact with one another can have an effect on backlash in one or both of the gear trains driving these components. For example, a first image-forming component may drive a second, adjacent component ahead of the motor that is driving that second component. This situation may result in a lack of control over the speed and/or position of the second component since its motor and associated motor control system are not actually driving that second component. Poor image quality may result for a period of time until the motor control system for that second component causes the motor to eliminate the backlash and positively engage the gear train to drive the second component. In some systems, it may take several printed pages to resolve this misregistration problem. Additional registration errors may ensue if a registration calibration procedure is performed in the image-forming device before the backlash is eliminated in one or more component drive trains.